sdb_array_insert chop strings sometimes

[radare]

this was a bug that it is fixed now in b71e11f.. but we have no tests for it, and we should do some more changes related to this that can be dangerous without a test

[radare]

�this was spotted by doing this in r2:

agn foo
agn bar
agn cow
aggk~nodes=
agraph.nodes=fo,ba,cow